Method: 1. Mix the flour, baking powder, soda bicarbonate and salt in a bowl. 2. Add the chocolate and mix well. 3. In a separate bowl, mix the butter and sugar. 4. Add eggs, one at a time, and beat well. 5. Add the vanilla extract and mashed bananas. 6. Add the flour mixture gradually and stir well until combined. 7. Transfer this to a greased loaf tin lined with parchment paper. 8. Place it into a preheated oven at 170C/325F. 9. Bake for 1 hour or until a skewer inserted in the centre comes out clean. 10. Remove and cool. 11. Slice and serve. 12. Store any remaining cake in an airtight container.